Prediction of immediate and long-term benefit after kyphoplasty of painful osteoporotic vertebral fractures by preoperative MRI

Background: It is unclear if an MR-detectable bone marrow edema is a prerequisite for pain reduction and morphological correction by kyphoplasty. This comparative trial evaluates clinical and radiomorphological outcomes after kyphoplasty of painful osteoporotic vertebral fractures with and without preoperative MR-detectable bone marrow edema for 1 year of follow-up.

Methods: Preoperative MR-images of 45 patients who received kyphoplasty for treatment of painful osteoporotic vertebral fractures were evaluated with regard to presence (n = 27) or absence (n = 18) of vertebral bone marrow edema. Pain scores (VAS 0-100) and radiomorphological measures (midline vertebral height, kyphosis angle) were analysed at baseline, postoperatively and after 12 months.

Results: In the "bone edema" group, pain scores improved from 72.7 to 46.8 (postoperative) and 48.0 (12 months, P < 0.001, both). In the group without preoperative bone edema, pain score improved from 70.7 to 60.3 (postoperative, P = 0.013) and to 50.1 (12 months, P = 0.001). Pain scores of both groups were significantly different directly postoperative (P = 0.026), but not after 12 months (P = 0.714). Vertebral height restoration was slightly greater in the "bone edema" group (10.2% vs. 7.8%, P = 0.289). Correction of the kyphosis angle was greater in the "bone edema" group (P = 0.014) compared to the "no bone edema" group (P = 0.838).

Conclusion: A preoperative MR-detectable vertebral bone marrow edema predicts a better short-term outcome after kyphoplasty, but is not a prerequisite for long-term pain reduction in patients with old, chronically painful osteoporotic vertebral fractures.